Modelling and Design Guidelines for Ram Air Ducts Using the Meredith Effect: Applied to an Organic Rankine Cycle Waste Heat Recovery System

With climate change posing increasing risks, the Advisory Council for Aviation Research and Innovation in Europe (ACARE) aims to reduce CO2 emissions by 75% and NOx emissions by 90% per passenger kilometer by 2050, compared to a baseline aircraft from 2000. The ARENA project addresses this by developing a waste heat recovery system using...

Flashback Detection and Suppression in Reheat Hydrogen Combustor

<br/>This research contributes to addressing climate change challenges through the examination of hydrogen combustion. It investigates the flow dynamics within a simplified model of Ansaldo Energia's GT36 reheat combustor using Large Eddy Simulation (LES) at a high pressure of 20 bar, focusing on the autoignition flashback phenomena observed....

Chemical Kinetics of Hydrogen-assisted Combustion of Kerosene

To meet the goals of the Paris agreement,sustainable aviation fuels, such as hydrogen, need be adopted on a large scale within the coming decades. Hydrogen-assisted combustion of kerosene is investigated as an intermediate step in the transition towards sustainable aviation. This study addresses the gaps in the current...

Comparison of LES techniques using a simplified model problem for non-premixed turbulent combustion

There is a need to examine the potential of alternative methods such as Variational Multiscale Method (VMM) for the ability to improve the efficiency of combustion simulations. However the computational expense of a LES run of a 3D turbulent non-premixed combustion problem is high due to the large variety of length and time scales in turbulent...

Effect of aeroelasticity on the acoustic signature of TOP contoured rocket nozzles in overexpanded conditions

TOP contoured nozzles, with large area-ratios, are commonly employed in rocket propulsion systems as they feature an excellent thrust-to-weight ratio. A significant shortcoming to this design is that, during the startup and shutdown transients of a LRE, the internal nozzle flow progresses through a series of overexpanded flow states - Free Shock...

Unsteady SpaRTA: Data-driven turbulence modelling for unsteady applications

Recent years have seen an increase in studies focusing on data-driven techniques to enhance modelling approaches like the two-equation turbulence models of Reynolds-averaged Navier-Stokes (RANS). Different techniques have been implemented to improve the results from these simulations. In particular, the main focus has been on overcoming the...

CFD Study on Flame Flashback in Low Swirl Premixed Burners

The energy transition from fossil fuels to renewable energy sources is crucial for climate resilience. In particular, hydrogen combustion in gas turbine combustors is expected to play an essential role in the energy transition. Hence, a fuel-flexible gas turbine combustor operating with a wide range of natural gas and hydrogen fuels is necessary...

An Experimental Investigation of the Operating Characteristics of a Flameless Combustor

This thesis covers the experimental characterisation of a multi-nozzle research combustor capable of achieving flameless combustion (FC). The combustor is operated with methane as fuel and air as the oxidiser, under an overall lean equivalence ratio ranging from 0.6-0.9. The work focused on designing and applying different experimental...

Using Artificial Intelligence for turbulent combustion modelling: Simplifying the conventional lookup tables

In reacting flows, detailed chemistry computations are usually avoided precomputing the thermochemical quantities as functions of a reduced set of variables such as the Flamelet Generated Manifold (FGM) approach[34]. Although it mitigates the calculations of detailed chemical mechanism, the memory requirement associated to store the lookup table...

Numerical modeling of turbulent hydrogen combustion for nuclear safety management

During a severe accident in a water­-cooled nuclear power plant, large quantities of hydrogen can be generated in the reactor core. The hydrogen mixed with air presents a potential risk of combustion when the hydrogen concentration reaches flammability limits. If combustion occurs, pressure loads can damage safety systems and even compromise the...

Modelling Differential Diffusion in Turbulent Non-Premixed Hydrogen Flames

In the future, fossil fuels will be replaced by renewable sources. Hydrogen seems to be a promising energy carrier (fuel). A lot of research has been conducted on the combustion of hydrogen, but the effect of the high diffusivity of hydrogen compared to other species (differential diffusion) was often not included in simulations of turbulent...

Numerical Study of Flow over a Rotating Cone under Axial and Non-Axial Inflow

Although significant strides have been made with regards to increasing the fuel economy of commercial passenger aircraft, the reduction of the environmental footprint remains of the utmost importance. The flow development over an aero-engine spinner will affect the velocity distribution over the fan of the engine and this affects the estimation...